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Keuffel & Esser 1740 Thacher Cylindrical Slide Rule

Keuffel & Esser 1740 Thacher Cylindrical Slide Rule

This paper, brass, and wood cylindrical slide rule has 20 sets of A, B, and C scales, with each set 47 cm in length. The scales are printed on paper that is glued around a sliding brass drum (with wooden handles) and on brass slats that are attached to a round brass frame on either end. The frame is screwed to a wooden base. A sheet of instructions for THACHER'S CALCULATING INSTRUMENT is glued along the top front of the base.

The right side of the paper on the drum is marked in italics: Patented by Edwin Thatcher [sic], C.E. Nov. 1st 1881. Divided by W. F. Stanley, London, 1882. Made by Keuffel & Esser Co. N.Y. A small silver metal tag affixed to the front right of the base is engraved: KEUFFEL & ESSER CO. (/) NEW-YORK (/) 663. Wayne Feely has suggested that K&E began manufacturing (as opposed to simply distributing) Thacher cylindrical slide rules in 1887, indicating 1887 is the earliest date for this example of the instrument. The latest date for the instrument is 1900, because K&E changed the design of the brass frame at that time.

The object is contained in a wooden case that bears no identifying marks. According to the accession file, the rule was found in a Smithsonian collections storage locker in the Arts & Industries Building about 1964.